Continuous passive motion (“CPM”) is a rehabilitation technique designed to assist in recovery of joint range of motion (“ROM”). CPM provides progressive passive ROM to an extremity through an externally applied force. Passive range of motion means that the joint is moved without the patient's muscles being used. CPM is used to maintain ROM and flexibility in joints in the early postoperative and rehabilitative period after surgery or injury when active movement might disrupt the repair process or is too painful to perform. In most patients after extensive joint surgery, attempts at joint motion cause pain and as a result, the patient fails to move the joint. This causes the tissue around the joint to become stiff and for scar tissue to form resulting in a joint which has limited range of motion and often may take months of physical therapy to recover that motion.
CPM is carried out by a continuous passive motion device, which is a motorized device that gradually and constantly moves the joint through a controlled range of motion. The exact range is dependent upon the joint, but in most cases the range of motion is increased over time. The device contains two parts; a carriage (also referred to herein as a frame) for support of the extremity and a controller that can be programmed for ROM, speed, pause and duration of treatment. During CPM therapy the joint area is secured in the device and the device is programmed to flex and extend the joint passively. CPM use is based on the theory that recovery will be accelerated by decreasing soft tissue stiffness, increasing ROM, promoting healing of joint surfaces in soft tissues and preventing the development of adhesions. Motion and stress are important for the maintenance of normal connective tissue and the healing of injured connective tissue. Motion enhances blood flow and decreases pain. CPM devices enable patients to get back quickly-or never lose-good motion in a joint.
The CPM devices that are currently being used for the treatment of knee injuries provide passive ROM but do not fully stretch the ligaments in the knee. Over the course of the treatment, the ligaments may stiffen. This limits the effectiveness of the treatment and results in longer recovery periods for the patients. Accordingly, there is a need for a device that simultaneously stretches the knee ligaments while at the same time providing passive ROM.